Engine generally refers to a gasoline engine, a diesel engine, a rotary engine, etc. A discharge system of an engine is provided with a catalyst for purifying exhaust gas and a noise eliminator, typically called a silencer or muffler, to reduce discharge noise.
The catalyst typically includes an oxidation catalyst, a reduction catalyst and a three-way catalyst. The configuration of such catalyst is of pellet type, Morris type (platelike) or the like.
The oxidation catalyst reduces the CO (carbon monoxide) and the HC (hydrocarbon) contained in the exhaust gas utilizing oxidation phenomenon, while the reduction catalyst reduces the NOx (nitrogen oxides) contained in the exhaust gas by reduction. The remaining three-way catalyst reduces the components of CO, HC and NOx contained in the exhaust gas.
Recently, there is a tendency for severely restricting the exhaust gas particularly from those vehicles having a diesel engine. Various countermeasures for the carbon contained in the exhaust gas as "black smoke" are being studied.
In the diesel engine, a light oil is sprayed into the drawn air after the air has been strongly compressed, thereby exploding the air and light oil without ignition. Since the diesel engine does not have a carburetor, as in a gasoline engine, the draw efficiency of air is high. Moreover, since the combustion time is long, the thermal efficiency is high. In addition, since the fuel consumption is less compared with the gasoline engine, the diesel engine is economical.
However, the diesel engine has inconveniences in that since the compressive pressure and explosive pressure are high, the weight of the diesel engine is increased and sounds and vibrations are increased, with the result that the maximum engine speed cannot be raised and a small size is difficult to obtain. Because of the reasons just mentioned, the diesel engine is generally used only on large vehicles.
In the conventional system for purifying exhaust gas, a three-way catalyst, for example, is provided on an intermediate part of a discharge system of the engine so that CO, HC and NOx as harmful components contained in the exhaust gas can be reduced. However, the three-way catalyst only has the function for reducing these three components, does not have the function for collecting carbon as a harmful component contained in the exhaust gas discharged from vehicles having a diesel engine.
The noise eliminator only has the function of reducing the discharge noise from a gasoline or diesel engine, and does not have the function of collecting carbon as a harmful component contained in the exhaust gas discharged from vehicles having a diesel engine.
As a result, there is such an inconvenience that carbon as black smoke is discharged from vehicles having a diesel engine, thus creating one of the causes of air pollution.
On the other hand, there is no device for spraying a fluid into an exhaust gas and collecting harmful components such as CO, HC, NOx, carbon, etc., and a development of such device is keenly needed.
Therefore, according to the present invention, in order to obviate the above inconveniences, there is provided a system for purifying exhaust gas comprising a cylindrical body portion formed by continuously arranging a plurality of chambers in line, a nozzle portion for jetting a fluid of a predetermined pressure in at least one chamber of the body portion, a compression portion for feeding a pressurized fluid through a pressure feed passage so that the fluid is jetted from the nozzle portion, a fluid reservoir portion connected to the compression portion through a first feed passage, a collection portion provided in the chamber, a collected fluid reservoir portion connected to the collection portion through a collection passage, a collection-use drawing portion disposed mid-way of the collection passage and adapted to collect the fluid and a product separated from an exhaust gas by the fluid from the nozzle portion, the collected fluid reservoir portion and the compression portion communicating with each other through a second feed passage, and control means communicating with and controlling the nozzle portion, compression portion and collection-use drawing portion in order to purify the exhaust gas.
By virtue of the accomplishment of the present invention thus constructed, when products are to be collected from the exhaust gas, a fluid of a predetermined pressure is jetted from a nozzle into at least one chamber of the body portion to cool the exhaust gas by the fluid so that the products are separated from the exhaust gas, the fluid and products are collected from a collection portion of the chamber, the fluid is returned to the collected fluid reservoir portion through the drawing portion, and the products are effectively removed from the exhaust gas.